NEW YORK — The United States Tennis Association on Thursday was found mostly liable for when Canadian player Eugenie Bouchard slipped on a wet locker room floor at the 2015 U.S. Open and hit her head, suffering what she said was a “serious head injury” that changed the course of her career.

A jury found Bouchard was partially at fault for what happened. It determined the USTA was 75 per cent to blame and Bouchard was 25 per cent to blame. What that means will be decided in another phase of the trial to determine damages, starting Friday.

Bouchard, 23, had just played in a mixed doubles match when she returned to the locker room at the Billie Jean King National Tennis Center in Queens shortly after 10 p.m. Minutes later, she fell on the tile floor of a physiotherapy room inside the locker room.

She sued the USTA for unspecified damages.

Bouchard told a jury in federal court in Brooklyn that she had taken two steps into the training area en route to take an ice bath when she lost her footing “and hit the back of my head on the floor.” She recalled being in “shock” as she found herself “staring at the ceiling.”

She testified she also felt a burning sensation on her skin from what her lawyers say was a powerful cleaning solution left on the floor.

Bouchard, once ranked No. 5 in the world and a Wimbledon finalist in 2014, testified that it was the USTA’s negligence that led to her slip and fall and the resulting injuries. She said she was forced to withdraw from the U.S. Open, where she was still in contention in singles and doubles, and from subsequent tournaments in China and Japan.

Bouchard, now ranked No. 116, said she hasn’t been the same player since she fell in the locker room. She left the courthouse on Thursday without commenting.

USTA lawyers countered that Bouchard should have known not to enter the area without being accompanied by a trainer or other tournament personnel and that the cleaning crew believed all the players had left for the night.

The USTA, the sport’s national governing body, had no comment on Thursday’s verdict.